2004 (W203) C180 Avantgarde Radio Interference and Engine Management Light

[lincolnshirelad]

Afternoon All,

First post on here so please go gently with my two (maybe related) issues.

I've had my MB for 2 years. It's a W203 with a 271 engine and has done 75,000 miles, been regularly serviced by an independent MB dealer and only just had an MOT. Aside from a new rear screen 2 years ago, due to radio interference with the HRW on, she's not given me much trouble.

I had a Parrot Mki 9200 and UNIKA fitted professionally a couple of months ago and the interference came back (Parrot works fine). I took it back to the auto-electrician who removed the radio/Parrot, inspected and tested everything (checking and replacing fuses, etc) but couldn't fix the fault - even by setting the radio electrics back to standard. The amplifier is fine as there wasn't any sound when the fuse was pulled. The HRW is doing it's job too. Could it be the SOT lead? It's a SOT-976 fitted.

Then on starting the car up the Engine Management Light came on. Driving home I noticed a lack of power when initially accelerating/on kick-down though the car will do 60mph without any issue.

The auto-electrician had a look at the car with his diagnostics and the following DTCs were thrown up:

P0445 - Evaporative Emission System Purge Control Valve circuit shorted
P0365 - Camshaft Position Sensor B circuit (Bank 1)
P0031 - HO2S Heater Control Circuit Low (Bank 1 Sensor 2)
P0037 - HO2S Heater Control Circuit Low (Bank 1 Sensor 1)
P0075 - Intake Valve Control Circuit (Bank 1)

On one occasion I still had 5 DTCs but P0445 and P0075 were replaced by P0010 and P0020.

You can clear the DTCs and Engine Management light with the ignition off and have 'no DTCs found' and drive her fine, but when you stop the car and start her up again the light and DTCs come back.

Live data with the car at idle as follows:

Fuel System: OL-FAU
Fuel System 2: Not used
Load Valve: 13.7
Coolant Temp: 73
Short Term FT: 0
Long Term FT: 0
Intake MAP: 34
Eng RPM: 730
Ign Adv: 10
Vehicle Speed: 0
Intake Air: 23
Airflow MAF: 0.00 (even with car revving at 3000rpm??)
Throttle Position: 3.1
Sec Air: Not used
O2 2 Bank : 0.435
Distance with MIL: 0
Wide O2 (S1 B1): 1.498

I've read on here that the Engine Management light can be for a variety of reasons e.g. loose/split breather pipe/vent hose, blocked oil breather, oil in wiring loom, LAMDA sensor, fouled plugs, MAF...Does this sound like an ignition problem (short circuit DTCs) rather than a fuel injection or exhaust system issue?

The auto-electrician is stumped on the interference as he's not changed anything to do with the HRW/Amplifier on visit 1 and even after re-inspecting her on visit 2 he's not tinkered with anything to do with the ECM.

I'm stumped as before the parrot installation the HRW and radio worked fine together for 2 years with no interference and the car has run 100% tip-top until after the second visit.I've never had the Engine Management light come on before. Service B is due on 1000 miles and there are 'no malfunctions' on the screen.

Any help and suggestions are gratefully received.

Thanks again.

LL

 

[television]

The engine will be the 271, The timing chain could be the problem as this can stretch, but it needs someone better than me to confirm it.

Re the interference this must be something that has been done on the antenna network and or amps, does the long range IR locking work well from a distance.

 

[lincolnshirelad]

Hi tv,

Thanks for the reply. The remote central locking works fine from a distance even through walls.

Could the timing chain just suddenly slacken?

It all seems too much of a coincidence especially with electrical work that's been undertaken i.e. the parrot kit.

LL

 

[television]

The 271 is known for the chain to stretch and start to throw codes before major engine damage takes place.

Re the antenna network all you can do at this stage it to double check every connection, a missing ground on the coax will cause this

 

[lincolnshirelad]

Thanks.

She's due for her B service so I may well bring that forward to this week and get the chain replaced at the same time.

 

[television]

Thanks.

She's due for her B service so I may well bring that forward to this week and get the chain replaced at the same time.

What is the mileage of the car, about 55k seems to be the starting point, it can be measured

 

[lincolnshirelad]

Hi Malcolm,

It's done 72k. I seem to remember that the timing belt may have been replaced by the independent retailer when I bought it 2 years ago, but I'll double check when I speak to them tomorrow.

Today has thrown up a new couple of codes (always 5 codes, just variations on a theme) 71 - Ambient Air Temperature Sensor Range/Performance 414 -Secondary Air Injection System Switching Valve "A" Circuit Shorted.

Thanks for your advice on this.

LL

 

[lincolnshirelad]

Oil in ECU

Hi Malcolm,

I took the car to the local MB Independent and they say that there's oil in the ECU (I've not seen it as I'm away) and the wiring loom may need replacing if it's contaminated that. A repair cost of ~ £1000 has been quoted.

I've read a few threads on staged repairs to minimise the costs e.g. fitting blockers, rinsing plugs with brake cleaner and blowing through with an air line, and a 200 mile follow up to see if the O2 sensor needs replacing.

I know you've said the ECU is tolerant to oil.

Is a split breather pipe on its own false hope? Any ideas gratefully received.

Did MB in the UK ever implement a recall for this very common (and potentially costly) problem as they did in the US?

Thanks.

LL

 

[television]

Is this the gearbox ECU, if so no one ever replaces the ECU or the cable,you just fix the pilot bush seal circa £30 and wash the ECU out, the wiring harness will drain itself.

 

[lincolnshirelad]

My wife told me they inspected the two L shaped plugs/boxes that attach to the right hand side (as you look at the car) of the main engine block??

Picture attached of what I think she described (not my engine - just for illustration)

Thanks.

LL

http://www.benzworld.org/forums/attachment.php?attachmentid=345548&stc=1&thumb=1&d=1291515274

 

[television]

OK I am with you now,,, you could go to MB and buy the cam magnet blocker plug again £30, pull the plug on the top front of engine, push the blocker in and replace the plug.

The oil could be a problem if it gets as far as the MAF, again you never replace the ECU as they wash down perfectly with brake cleaner, the oil in the cable will go away, but the ECU and MAF may need to be cleaned once or twice.

I think you need a better indie.

Oil is not conductive, it has a capacitive effect, but nothing to case any harm in the running.

 

[lincolnshirelad]

Thanks Malcolm.

I will actually speak to the indie tomorrow and suggest this course of action.

If I'd have known about this problem I'd have had the preventative work done when I bought the car. Interesting that MB North America issued a recall for this but the UK never did??

Missed the 'unknown unknown' of having to put 2 x 1 litre of oil in the car over the past year. Had I known about the warning sign I may have been able to act sooner.

Pardon my ignorance, what is the MAF please?

LL

 

[lincolnshirelad]

Malcolm,

In your opinion is the car safe to drive, even on short trips of 15 minutes?

Thanks.

LL

 

[television]

Yes and why not, it may run a little rough and external problems and nothing to cause any damage.

 

[lincolnshirelad]

Thanks Malcolm, at least the wife can do the school run in the morning.

I'll let you know how I get on.

LL

P.S. MAF = Mass Air Flow sensor?

 

[television]

Thanks Malcolm, at least the wife can do the school run in the morning.

I'll let you know how I get on.

LL

P.S. MAF = Mass Air Flow sensor?

It is this part sets up the fueling for the engine, it measures the air temp coming in. it works in conjunction with the 02 senor, the 02 sensor measures the exhaust content, if incorrect then the info is fed back to the MAF and changes made to the fueling.

 

[lincolnshirelad]

Ta.

Is the O2 sensor the same as the lambda sensor?

LL

 

[television]

Ta.

Is the O2 sensor the same as the lambda sensor?

LL

Yes that is the same thing, with this, this is the only thing that can turn on the engine lamp, the MAF cannot directly. The 02 sensor has a stored range that is stored in the engine ECU. If the MAF has failed or is failing, this can cause the 02 sensor to go out of its stored range and turn on the engine lamp, so sometimes you have to read between what the fault codes are telling you.

 

[lincolnshirelad]

Hi Malcolm,

I spoke with the Indie this morning. They were planning on replacing the Isolation wires only and cleaning out the ECU/Plugs. The O2 (Lambda) sensor seems fine.

I asked them to replace the Cam sensors too.

I suggested that I run the car for a couple of hundred miles and see how it goes; maybe cleaning the plugs/sensors again.

Car goes in on Monday at a cost of parts plus 2 hours labour.

Thanks.

LL

 

[lincolnshirelad]

Update

Hi Malcolm,

Just a quick update on the saga. I had the car into the indie on Monday. They fitted the cam sensors, isolation wires and (after taking it off the car) cleaned the ECU drying it thoroughly overnight. The contamination wasn't that bad apparently (a misting) and the lambda sensor was clean.

Now, the EML is on all the time and has random new codes (P2015, P2017, P2021, P2022, P2034) which can't be cleared.

We thought as the ECU had been off the car maybe it needed re-aligning with the VIN; which was something the indie couldn't do.

So, I took the car to the MB main dealer in Lincoln who kindly ran the STAR diagnostics for free and found the same codes which are "stored and current" so they can't clear them.

The main dealer thinks it could be:
i) a wiring issue (remember the HRW/radio issue post-fitting of the parrot kit), or
ii) oil in the loom

Highly unlikely to be the timing chain having slackened due to the codes apparently.

So, as the indie can't do this, it's booked in with the main dealer for next week. Loom (only if required) is £250 and labour is £70ph.

Your thoughts are gratefully received.

Thanks again.

LL